摘要：He struck a match, and held it at arm's length. （他划了一根火柴，举到尽可能远处） [柯林斯高级学者辞典]

不借助工具，人能操作的最远距离就是手臂尽可能打开的那么远，所以at arm's length是“离自己身体尽可能远”，如

【例句1】He held the dirty rag at arm's length (= as far away from his body as possible). （他把脏抹布举得远远的。） [牛津高级学者辞典]

【例句2】He held the snake at arm's length. (他把蛇远远拿着。)[剑桥学术内容词典]

【例句3】He struck a match, and held it at arm's length. （他划了一根火柴，举到尽可能远处） [柯林斯高级学者辞典]

at arm's length也引申用于情感方面，表达“不让对方跟你走得很近”，如

【例句4】She kept him at arm's length for months. （她与他冷淡了几个月。）[牛津高级学者辞典]

【例句5】I always had the feeling she was keeping me at arm's length. （我一直觉得她在和我保持距离。）[剑桥高级学者辞典]

【例句6】She had always kept his family at arm's length. （她总是和他的家人保持距离。） [柯林斯高级学者辞典]

【例句7】He keeps all his clients at arm's length.（他与所有客户保持一定距离。 ） [牛津高级学者辞典]

【例句8】Petra keeps all men at arm's length to avoid getting hurt. （佩特拉与所有男人保持距离，以免受伤。 ）[朗文当代英语词典]

注意，arm的典型用法是可数名词，但在上述用法中，他前面不要加“件词”。an arm's length，the arm's length，your/his arm,都有倾向“实物化”和“字面义”的解读。

at arm's length的用法在1655年就开始出现，当时的拼法是at armes length。此armes是复数，还是所有格，待考证。

中世纪欧洲喜欢用剑来决斗。决斗者应尽可能打开手臂，这样让自己剑尖远离自己，刺中对方。可能是因为这个历史原因，有了at arm's length的习语。

随着时间的推移，此习语逐渐演变成更具比喻意义的用法，用来表达与它人或别事保持安全距离。

来源：捷宇时尚家一点号